Closing ends of metal tubes



Sept. 21, 1943. R, KNOX 2,329,770

CLOSING ENDS OF METAL TUBES Filed April 28, 1941 INVENTOR. fund 7? K270)kwwa f of the ends of metal tubes.

Patent d Sept. 21, 1943 (LOSING ms F ME'I'AL TUBES David R. Knox,Detroit, Mich, assignor to Bundy Tubing Company, Detroit, Mich, acorporation of Michigan Application April 28, 1941, Serial No. 390,708

3 Claims.

This invention relates to the closing or sealing The principal object ofthe invention is to provide a novel structure for'closing or sealing theend of a metal tube and a method in'which all operations are performedon the tube at the end to be sealed and without requiring the insertionof an instrument or tool from the opposite end of the tube. I

The structure of the invention is one which may be employed for a numberof p rp ses. For example, the structure may be used on tubing which isto be used with refrigeration equipment, and'the length of tube with itssealed ends may be shaped and fashioned into the desired coils or shapesand the final steps may be that of opening the tube ends and chargingthe same with refrigerant. Thus the interior of the tube is kept cleanand devoid from a collection of extraneous material. Another placeof useis in bombs or explosive shells where a closed tube is used for ignitionpurposes.

thereon and magnetically held, and then the plunger advances the discinto the tube as substantially illustrated in Fig. 2. Insofar as themethod is concerned, the movement of the feeding plunger and the openingand'closing of the holding device and the placingof the tube therein,may be done by hand or by suitable mechani- The structure and the methodare disclosed in the accompanying drawing wherein Fig. 1 is a viewillustrating the tube and sealillustrated apparatus for performing themethod. Fig. 2 is a view similar to Fig. 1 showing the Fig. 3 is a viewshowing the final step of swaging the end of the tube for sealingpurposes.

Fig. 4 is an enlarged cross sectional view showing the sealed end of thetube and illustrating how the metal flows.

In disclosing the invention both as to method and structure, it appearsto be most expedient In Fig. 1, the tube is'illus'trated at I while aholder or clamping device forothe tube is illustrated at 2. This.clamping device may be made in any suitable way to be opened and closedso that a length of tube may be placed therein, and then gripped andheld in position. A swaging tool' is illustrated at 3, and it isprovided with a bore 4 therethrough, one end of which has an outwardflare as at 5. A sealing member is illustrated at i,

ing element associated with diagrammatically cal means.

The disc preferably has a snug fit with the interior of the tube so thatit is-more or less held positioned frictionally as well' asmagnetically. Now, as'shown in Fig. 3, the swaging tool- 3 is advancedtoward the end of the tube and the inclined walls 5 engage the end ofthe tube to swage the same and thus contract'the end of the-tube assubstantially illustrated in Figs. 3 and 4. This gives the end of thetube a sort of tapered formation. The disc is originally positioned sothat it is'subjected to the pressure of the swaging tool. Furthermore,the'metal of the.

tube is swaged to an extent such that the sealing disc is subjectedperipherally to pressure and deformed. As illustrated in Fig. 4, thesealing disc is deformed into'a concavo-convexformation withthebonvexity facing inwardly of the tube and the concavity facingoutwardly; The

' disc is thus deformed with its concavity facing sealing elementinserted in the end of the tube.

' to proceed in the order of the steps of the process.

outwardly apparently because the forces applied to the disc are greaterin the region adjacent the side which becomes concave than in the regionadjacent the side which becomes -convex. The metal in the tube wall atthe swaged end, being forced into a smaller radius, .is caused to flow,

with the result that the .wall becomes thickened.

Yet the disc offers a substantial resistance to deformation. As aresult, the metal in the wall of the tube flows over or into overlappingrelationship with the peripheral edges of the disc as illustrated at Xand Y.

and this is. in the form of a metal disc. A feeding plunger for the discis illustrated at 8, and for Y the purpose of holding the disc it mayhave a magnetic tip 9.

In sealing a tube, one end of the length of tube is placed in the holder2 with its end abutillustrated in Fig. 1. The feed plunger is retingagainst the swaging tool substantially as I The structure, accordingly,is one capablc of withstanding substantial internal pressures. Themethod is preferably performed with the, metals in a cold condition,that is to say, at room temperature, but the engagement at theinterfaces between the tube wall and the disc is such as to withstandlarge internal pres ure without I leakage. Where conditions of usrequire, it is, of course, within the invention "to so unite the discand tube wall at the seam by molten sealing metal as for example, by theapplication of solder or brazing metal.

I claim:

1. The method of closing the end of a metal tube which comprises,placing a substantially flat tracted so that a sealing disc may beplaced metal disc having a diameter substantially corresponding to theinternal diameter of the tube within the end of the tube in a positionso that the end of the tube projects beyond the disc, sub-. jecting theprojectingend of the tube and the portion thereof surrounding the discto external pressure with the tube and disc in a cold state to reducethe projecting end of the tube to an internal diameter less than thediameter of the disc and to deform the disc into a concavo-convexformation withthe concavity thereof facing outwardly and to cause themetal of the tube wall to thicken and flow over the peripheral edges ofthe projecting end of the tube to an internal diameter less than that ofthe diameter of the deformed disc and to cause the metal of the tubewall to thicken and flow over the peripheral edges of the disc.

3.'The method of closing the end of a metal tube which comprises,placing a substantially flat metal disc having a diameter substantiallycorresponding to the internal diameter of the tube within the end of thetube in a position-so that the end of the tube projects beyond the disc,holding the tube in a fixed position, swaging the end of the tube byadvancing a swaging tool axially of the tube and into swaging engagementwith the end of the tubewith the tube and disc in a cold state to reducethe projecting end of the tube to an temal diameter less than thediameter of the c and to partially collapse the disc into concavo-convexform with its concavity facing outwardly and to cause the metal of the 1tube wall to thicken and-flow over the peripheral edges of the disc.

DAVID R. KNOX.

